In existing video coding as presently practiced, algorithms are used inside the codec to recognize image changes, in order to find the image portions that are to be compressed. The calculation time needed to discover such image changes (a person's head has moved, etc.) is relatively long and, together with the transmission bandwidth, limits the number of moving images that can be processed per second.
U.S. Pat. No. 5,216,596 discloses a telepathology system. A workstation is set up at a remote location and receives images from a preparation (tissue) that is to be examined with a microscope. The microscope images are recorded with a conventional video camera, and displayed at the remote location on a conventional video monitor. A or coding of the image data is accomplished after imaging. The system presented here is tied to analog transmission links, and cannot achieve the necessary resolution in a conventional digital network. Coding is also ruled out because of the analog transmission.